Ecopak is part of a new generation of outdoor fabrics that grew out of technologies used in high performance sailcloth. These fabrics are "laminates" that are made by bonding multiple layers of fabric and film into one final material. There is a huge range of different styles within this laminate category but in general laminates are lighter, stiffer and less stretchy (hold their shape better), and more waterproof than a tradition woven fabric with similar durability.
Ecopak covers a range of laminate fabrics developed by Challenge Sailcloth using largely recycled polyester fabrics and films (instead of virgin nylon) and a less resource intensive manufacturing process than most previous laminate options. It was the first significant release of recycled laminates and remains the broadest range of recycled colours and fabric styles.
Ecopak comes in two main categories, EPX and EPLX.
EPX laminates have three layers, a fabric outer, a stabilizing cross ply, and a fabric backing layer. These fabrics are light and supple and make for excellent thin and light bags. The fabric backing give thin and light single layer bags a bright interior and protects the fabric from abrasion and damage from whatever you throw in them. The adhesive that bonds these layers together forms a waterproof barrier and gives these fabrics a truely "waterproof" rating in lab testing. In our testing however, we've found seams in these EPX fabrics to be slightly more prone to wetting out than other laminates.
EPLX laminates have a different three layer construction, with a fabric outer, a stabilizing cross ply, and a film backing layer. This film backing provides a more substantial waterproof barrier and in some cases allows stitching that might compromise that waterproofness to be "taped" and sealed. For the most water resistant finished bag consider choosing EPLX fabrics. EPLX is stiffer and more prone to creasing and crumpling vs EPX and the film backing is less suited to thin and light single layer bags that would leave that backing exposed.